I was prefering solution 3 a bit more, especially for higher bonus in higher levels.
But your point convinced me, I will analysis how to do with solution 1.
But want to ask if you are already using the "refined" clips, and still find it inadequate?
They have +50% damage over "standard" clips.
Although they are more expensive, they are made of basically "free" resources.
I am sure I don't have any damage-bonus to particle turrets, up to current version.
But I get some similar bug like what you mentioned, when loading a save game from 0.17.16.
Actually, I NOW get different behaviour from loading my "same megabase save game", but saved in different versions...
- 0.16.51: No damage bonus for any particle turrets. (As expected. It should be the normal case.)
- 0.17.4: Same as above 0.16.51. (So still normal.)
- 0.17.6: ONLY force cannon got +190% damage bonus. (It should not appear!)
- 0.17.7: Same as above 0.17.6. (Bad too.)
- 0.17.16: OTHER 4 particle turrets EXCEPT force cannon got +190% damage bonus... Also messed up the vanilla gun turret to +160%... (Should be +190%!) Artillery turret and wagon got +190%... (Should not have any!)
Conclusion?
I have not touched the technology or damage bonus part since Alien Tech 0.17.0 update, so it can't be from me.
And from the pattern above, it seems the source comes from vanilla game 0.17.5 update (the big and buggy update about mining productivity changes...) and the consequence updates which tried to correct those bugs...
So, do you have an old save from 0.16.51 or before 0.17.5? Please load it and tell me if the damage bonus is messed up or not.